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/* * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /* * This file is available under and governed by the GNU General Public * License version 2 only, as published by the Free Software Foundation. * However, the following notice accompanied the original version of this * file: * * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos * * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * * Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * * Neither the name of JSR-310 nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ package java.time.temporal; import java.time.DateTimeException; import java.util.Objects; /** * Framework-level interface defining read-only access to a temporal object, * such as a date, time, offset or some combination of these. * <p> * This is the base interface type for date, time and offset objects. * It is implemented by those classes that can provide information * as {@linkplain TemporalField fields} or {@linkplain TemporalQuery queries}. * <p> * Most date and time information can be represented as a number. * These are modeled using {@code TemporalField} with the number held using * a {@code long} to handle large values. Year, month and day-of-month are * simple examples of fields, but they also include instant and offsets. * See {@link ChronoField} for the standard set of fields. * <p> * Two pieces of date/time information cannot be represented by numbers, * the {@linkplain java.time.chrono.Chronology chronology} and the * {@linkplain java.time.ZoneId time-zone}. * These can be accessed via {@linkplain #query(TemporalQuery) queries} using * the static methods defined on {@link TemporalQuery}. * <p> * A sub-interface, {@link Temporal}, extends this definition to one that also * supports adjustment and manipulation on more complete temporal objects. * <p> * This interface is a framework-level interface that should not be widely * used in application code. Instead, applications should create and pass * around instances of concrete types, such as {@code LocalDate}. * There are many reasons for this, part of which is that implementations * of this interface may be in calendar systems other than ISO. * See {@link java.time.chrono.ChronoLocalDate} for a fuller discussion of the issues. * * @implSpec * This interface places no restrictions on the mutability of implementations, * however immutability is strongly recommended. * * @since 1.8 */ public interface TemporalAccessor { /** * Checks if the specified field is supported. * <p> * This checks if the date-time can be queried for the specified field. * If false, then calling the {@link #range(TemporalField) range} and {@link #get(TemporalField) get} * methods will throw an exception. * * @implSpec * Implementations must check and handle all fields defined in {@link ChronoField}. * If the field is supported, then true must be returned, otherwise false must be returned. * <p> * If the field is not a {@code ChronoField}, then the result of this method * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)} * passing {@code this} as the argument. * <p> * Implementations must ensure that no observable state is altered when this * read-only method is invoked. * * @param field the field to check, null returns false * @return true if this date-time can be queried for the field, false if not */ boolean isSupported(TemporalField field); /** * Gets the range of valid values for the specified field. * <p> * All fields can be expressed as a {@code long} integer. * This method returns an object that describes the valid range for that value. * The value of this temporal object is used to enhance the accuracy of the returned range. * If the date-time cannot return the range, because the field is unsupported or for * some other reason, an exception will be thrown. * <p> * Note that the result only describes the minimum and maximum valid values * and it is important not to read too much into them. For example, there * could be values within the range that are invalid for the field. * * @implSpec * Implementations must check and handle all fields defined in {@link ChronoField}. * If the field is supported, then the range of the field must be returned. * If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown. * <p> * If the field is not a {@code ChronoField}, then the result of this method * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessorl)} * passing {@code this} as the argument. * <p> * Implementations must ensure that no observable state is altered when this * read-only method is invoked. * <p> * The default implementation must behave equivalent to this code: * <pre> * if (field instanceof ChronoField) { * if (isSupported(field)) { * return field.range(); * } * throw new UnsupportedTemporalTypeException("Unsupported field: " + field); * } * return field.rangeRefinedBy(this); * </pre> * * @param field the field to query the range for, not null * @return the range of valid values for the field, not null * @throws DateTimeException if the range for the field cannot be obtained * @throws UnsupportedTemporalTypeException if the field is not supported */ default ValueRange range(TemporalField field) { if (field instanceof ChronoField) { if (isSupported(field)) { return field.range(); } throw new UnsupportedTemporalTypeException("Unsupported field: " + field); } Objects.requireNonNull(field, "field"); return field.rangeRefinedBy(this); } /** * Gets the value of the specified field as an {@code int}. * <p> * This queries the date-time for the value of the specified field. * The returned value will always be within the valid range of values for the field. * If the date-time cannot return the value, because the field is unsupported or for * some other reason, an exception will be thrown. * * @implSpec * Implementations must check and handle all fields defined in {@link ChronoField}. * If the field is supported and has an {@code int} range, then the value of * the field must be returned. * If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown. * <p> * If the field is not a {@code ChronoField}, then the result of this method * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)} * passing {@code this} as the argument. * <p> * Implementations must ensure that no observable state is altered when this * read-only method is invoked. * <p> * The default implementation must behave equivalent to this code: * <pre> * if (range(field).isIntValue()) { * return range(field).checkValidIntValue(getLong(field), field); * } * throw new UnsupportedTemporalTypeException("Invalid field " + field + " + for get() method, use getLong() instead"); * </pre> * * @param field the field to get, not null * @return the value for the field, within the valid range of values * @throws DateTimeException if a value for the field cannot be obtained or * the value is outside the range of valid values for the field * @throws UnsupportedTemporalTypeException if the field is not supported or * the range of values exceeds an {@code int} * @throws ArithmeticException if numeric overflow occurs */ default int get(TemporalField field) { ValueRange range = range(field); if (range.isIntValue() == false) { throw new UnsupportedTemporalTypeException( "Invalid field " + field + " for get() method, use getLong() instead"); } long value = getLong(field); if (range.isValidValue(value) == false) { throw new DateTimeException("Invalid value for " + field + " (valid values " + range + "): " + value); } return (int) value; } /** * Gets the value of the specified field as a {@code long}. * <p> * This queries the date-time for the value of the specified field. * The returned value may be outside the valid range of values for the field. * If the date-time cannot return the value, because the field is unsupported or for * some other reason, an exception will be thrown. * * @implSpec * Implementations must check and handle all fields defined in {@link ChronoField}. * If the field is supported, then the value of the field must be returned. * If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown. * <p> * If the field is not a {@code ChronoField}, then the result of this method * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)} * passing {@code this} as the argument. * <p> * Implementations must ensure that no observable state is altered when this * read-only method is invoked. * * @param field the field to get, not null * @return the value for the field * @throws DateTimeException if a value for the field cannot be obtained * @throws UnsupportedTemporalTypeException if the field is not supported * @throws ArithmeticException if numeric overflow occurs */ long getLong(TemporalField field); /** * Queries this date-time. * <p> * This queries this date-time using the specified query strategy object. * <p> * Queries are a key tool for extracting information from date-times. * They exists to externalize the process of querying, permitting different * approaches, as per the strategy design pattern. * Examples might be a query that checks if the date is the day before February 29th * in a leap year, or calculates the number of days to your next birthday. * <p> * The most common query implementations are method references, such as * {@code LocalDate::from} and {@code ZoneId::from}. * Additional implementations are provided as static methods on {@link TemporalQuery}. * * @implSpec * The default implementation must behave equivalent to this code: * <pre> * if (query == TemporalQueries.zoneId() || * query == TemporalQueries.chronology() || query == TemporalQueries.precision()) { * return null; * } * return query.queryFrom(this); * </pre> * Future versions are permitted to add further queries to the if statement. * <p> * All classes implementing this interface and overriding this method must call * {@code TemporalAccessor.super.query(query)}. JDK classes may avoid calling * super if they provide behavior equivalent to the default behaviour, however * non-JDK classes may not utilize this optimization and must call {@code super}. * <p> * If the implementation can supply a value for one of the queries listed in the * if statement of the default implementation, then it must do so. * For example, an application-defined {@code HourMin} class storing the hour * and minute must override this method as follows: * <pre> * if (query == TemporalQueries.precision()) { * return MINUTES; * } * return TemporalAccessor.super.query(query); * </pre> * <p> * Implementations must ensure that no observable state is altered when this * read-only method is invoked. * * @param <R> the type of the result * @param query the query to invoke, not null * @return the query result, null may be returned (defined by the query) * @throws DateTimeException if unable to query * @throws ArithmeticException if numeric overflow occurs */ default <R> R query(TemporalQuery<R> query) { if (query == TemporalQueries.zoneId() || query == TemporalQueries.chronology() || query == TemporalQueries.precision()) { return null; } return query.queryFrom(this); } }